The pick sets up what will be a critical decision for Snyder in naming someone to the court in which Republican nominees hold a 4-3 edge. A handful of names have surfaced including Michigan Appeals Court Judges Kirsten Frank Kelly, Jane Markey and Pat Donofrio.

“Snyder has to be careful with this,” said Bill Ballenger, editor of the Inside Michigan Politics newsletter. “Snyder … has to make sure that his choice is a solid conservative, because many conservatives in the Republican Party have doubts about Snyder’s allegiance to their point of view.”

Snyder said at a news conference he has not chosen Corrigan’s successor but will do so by next Friday, when she will step down. The choice is critical because the court is expected to settle redistricting disputes following the 2010 census.

Corrigan will join Snyder’s six-member inner cabinet. In addition to running a huge department, Corrigan will be group executive for “people” departments, meaning the heads of community health, education and civil rights will report to Snyder through her.

Snyder called Corrigan “a true champion of children and their families.”

Jack Kresnak, CEO of the advocacy group Michigan’s Children, said the “balance between reducing services and protecting children will be a defining moment for this administration and I think that Maura Corrigan is probably the best equipped person I know.”

But the liberal group Progress Michigan said Corrigan has “put large corporations and extremist ideology ahead of the safety and well-being of consumers and children.”

First elected to the high court in 1998, Corrigan has an interest in adoption and other issues affecting children, and has served on boards of youth welfare organizations. She received Vista Maria’s Child Advocate of the Year Award in 2005, the Congressional Coalition on Adoption Angels in Adoption award in 2005, and a U.S. Department of Health and Human Services award in 2002 for improvements to Michigan’s child support system.

With about 20 percent of the state’s population receiving some form of food, housing or health coverage assistance, “Michigan has a huge population of people in need — a population that that DHS serves,” Corrigan said Thursday.

Among the possible successors, Kelly, elected to the Court of Appeals in 2000, is a frontrunner, Ballenger said. Though a Republican nominee, her vintage name evokes the popular former Attorney General Frank Kelley, a Democrat.

Markey, who has spent nearly 16 years on the Court of Appeals, was a Republican nominee for the Supreme Court in the November election.